November 28, 2022

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How does flu vaccine prevent the flu virus?

How does flu vaccine prevent the flu virus?


How does flu vaccine prevent the flu virus? In the winter every year, influenza vaccines become a hot topic. In the past, it was relatively simple to choose influenza vaccines, because there was only one type of influenza vaccine—inactivated influenza vaccines. Generally speaking, inactivated influenza vaccines contain “dead” influenza. Virus influenza vaccine. This year, the influenza vaccine family has one more category-live attenuated nasal spray influenza vaccine, which is a vaccine containing “live” influenza virus. How to choose between these two vaccines? It has troubled many people, it’s time to popularize science!

How does flu vaccine prevent the flu virus? 


How does flu vaccine prevent the flu virus?

Contrary to what most people think, in fact, vaccines do not directly target diseases or viruses like drugs. It is not so much that influenza vaccines prevent influenza viruses. It is more accurate to say that influenza vaccines help the human immune system recognize influenza viruses early. The human body produces various antibodies (immunoglobulins) and immune cells against influenza viruses. These antibodies and immune cells against influenza viruses are the protagonists who really play a preventive role against influenza viruses. Therefore, it is the human immune system that ultimately defeats the virus.

The human immune system has a characteristic. As long as an unknown virus enters the human body, after a period of time, the immune system will always find and recognize it, and then produce various antibodies and immune cells to deal with the virus. Scientists have used the characteristics of the human immune system to develop a vaccine. In layman’s terms, vaccination is a way to send a virus that does not cause disease to the human body and stimulate the body to produce antibodies and immune cells against the virus. Therefore, most of the effective ingredients of vaccines are viruses.


How does flu vaccine prevent the flu virus?


Are vaccines made of influenza viruses safe?

Thinking of sending so many influenza viruses into the body, many people hesitate again. Since it is a virus, will they get sick?

In order to allow the body’s immune system to recognize the virus without getting sick, scientists developed the “corpse” or “fragment” of the influenza virus into an inactivated vaccine; the influenza virus that weakened its toxicity and did not cause disease was developed into a live attenuated vaccine. For safety, a phase III clinical trial is required before the vaccine is marketed. Only when the test results meet the national requirements can it be allowed to be marketed. Therefore, in terms of safety, regardless of whether the vaccine is inactivated or live attenuated, all vaccines we can get It is guaranteed.

It is worth mentioning that the live attenuated influenza virus contained in this newly launched nasal spray influenza vaccine is provided annually by the World Health Organization. In addition to its non-pathogenic characteristics, it also has the characteristics of being afraid of heat. It can only replicate limitedly in the lower parts of the upper respiratory tract, which can stimulate the body to produce various antibodies (immunoglobulins) and immune cells against influenza viruses. To achieve the effect of preventing influenza. This live attenuated virus can hardly replicate in areas with higher temperatures such as the lungs, so there is no need to worry about whether it will cause infections due to nasal spray flu vaccine.



Why should the flu vaccine be given before the flu season?

Since it takes some time for the human body to recognize the virus to produce antibodies and immune cells, the vaccine will not work as quickly as the medicine. Therefore, experts recommend that everyone get the flu vaccine early before the flu season. Generally, inactivated influenza vaccines produce antibodies in 2-4 weeks, while nasal sprays of live attenuated influenza vaccines can produce antibodies in 3 days. Don’t underestimate the ten-day gap. During the flu season, especially when people around you already have flu, antibodies are produced one day later, and the risk of infection is greatly increased!



Why is it recommended that the elderly and children be vaccinated against influenza?

Healthy adults have a strong immune system. After being infected with influenza virus, due to the rapid production of antibodies and the large number of antibodies, the virus that enters the body is quickly eliminated, and may be cured after a few days of rest. However, people with weak immunity, such as the elderly and children, have a weakened or weak immune system. Once infected with influenza virus, the production of antibodies and immune cells is slow and small. Not only does the disease lasts for a long time, but the virus attacks all parts of the body in severe cases. Organs are more likely to cause various complications and even life-threatening. Therefore, experts recommend that the elderly and children be vaccinated against influenza in time.



Can I lose the flu after getting the flu vaccine?

There are many types of influenza viruses. The major impacts on humans are influenza A and B viruses. There are hundreds of subtypes of influenza A viruses, among which H1N1 and H3N2 subtypes are more popular, and influenza B viruses are only two types: Victoria and Yamagata. Each line, the influenza vaccine each year is developed by the epidemic virus type predicted and provided by the World Health Organization (WHO). Although the influenza vaccine basically covers the pandemic influenza virus type, there are subtypes that are not covered. Moreover, there may be a mismatch in predictions, so influenza vaccination cannot prevent all influenza viruses.

Inactivated influenza vaccines only produce antibodies against the virus types contained. No matter the 3 or 4 valence influenza vaccines, they all contain the H1N1 and H3N2 subtypes of influenza A virus. The difference is that the 3 valence contains only one influenza B virus. Victoria line, 4 valence is two lines of Victoria and Yamagata containing influenza B virus.

Studies have shown that, in addition to preventing the virus types contained in the live attenuated influenza vaccine, it can also generate cross-immunity, and it also has a certain preventive effect on influenza viruses other than the virus types contained in the vaccine. Therefore, even if it is a live attenuated nasal spray influenza vaccine containing 3 influenza viruses, the actual scope of prevention is not limited to the 3 influenza viruses. The advantage of this cross-protection is that once the virus strain contained in the vaccine does not match the influenza virus type, it also has a certain preventive effect.



Does nasal spray flu vaccine spray the nose really prevent it?

Picture vaccines are usually given by injection and oral administration. Is the effect of nasal spray really good? In addition, the inactivated influenza vaccine needs to be injected with 0.5ml to have a preventive effect. The nasal spray flu vaccine only sprays 0.1ml into each nostril, and the dose is much smaller!

Before asking this question, let’s think about how we got the flu. We usually inhale a small amount of influenza virus through the nasal cavity. After the virus enters the nasal mucosal cells, it multiplies in large numbers, and then enters body fluids and spreads throughout the body to cause diseases. You will find that we didn’t breathe in many influenza viruses at the beginning, but after the virus replicated in large numbers, it was enough to make us sick.

Similarly, although the dose of live attenuated influenza vaccine is small, the live attenuated virus is delivered to the mucous membrane of the nasal cavity through nasal spray. It can effectively replicate in the lower temperature part of the upper respiratory tract. When the human immune system is found in the upper respiratory tract When a large number of live attenuated influenza viruses, a large number of antibodies and immune cells will be produced to prevent influenza. In layman’s terms, the live attenuated nasal spray flu vaccine actually simulates a military exercise involving the invasion of influenza viruses, so that the human body naturally produces antibodies and immune cells to achieve the purpose of preventing influenza. The natural way to stimulate the immune system can mobilize all the functions of the immune system, resulting in a more comprehensive and thorough immune effect.



What secret weapon does the nasal flu vaccine have?

Compared with the traditional injection vaccination method which mainly relies on humoral immunity, the live attenuated influenza vaccine is vaccinated by nasal spray, which simulates the natural immune process of the human body and can mobilize all the functions of the immune system, including mucosal, cellular and humoral immunity. Way to work. It first produces mucosal immunity in the nasal mucosa to prevent influenza viruses entering from the nasal cavity from infecting mucosal cells; produces cellular immunity to eliminate influenza viruses that enter the cells; produces humoral immunity to eliminate influenza viruses that enter body fluids, which may invade the nasal mucosa Influenza viruses in the upper, intracellular and body fluids can be effectively prevented.

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